Poirot’s Christmas is interrupted by Simeon Lee, who believes his life is threatened. Simeon is soon killed and his diamonds stolen.

A salacious government scandal hits close to home for Elizabeth and Philip. Elizabeth retreats to Scotland for rest during a difficult pregnancy.

A secret World War II document opens Elizabeth’s eyes to grim realities about a family member. The Duke of Windsor campaigns to re-enter public life.

When Elizabeth and Philip throw a grand party for their 10th anniversary, both Margaret and the new Prime Minister experience romantic tribulations.